As a dominant open-water force, the Royal Navy did not traditionally expend much effort on such an inherently defensive type as the gunboat, but there were times and situations in which they were the only answer. The defence of Gibraltar was one. Early gunboats were very boat-like, with a single gun, usually forward and on a slide and averaged about 40 tons, but from 1794 a new type of far larger gunboat, of around 150 tons began to be constructed.

Initially rated as 'gunboats', then 'gun vessels' and carrying two long 24pdrs firing forward and twelve 18pdr carronades, they were soon re-rigged as brigs each under the command of a lieutenant, but were not popular assignments in their largely defensive role. As the type developed, the evolution of the gunbrig into a cruiser — albeit more suited to coastal waters — left a gap to be filled by a more modest gunboat, and large numbers of the traditional launch-like oared craft were built. Best known of the specific designs is 'Commissioner Hamilton's gunboat', designed by Captain Thomas Hamilton, a Commissioner of the Transport Board, and a man with many ideas on naval architecture. His gunboat had one long gun forward on a slide that seems to have allowed limited traverse, and a carronade aft on a turntable .